A typical electronic circuit includes a plurality of electronic devices that are interconnected to one another via conductive buses/traces on a surface of a dielectric substrate. The combination of the buses/traces and the substrate is called a circuit board.
A known circuit board includes conductive buses/traces on a top surface thereof as well as buses/traces embedded in the body of its substrate. To reach the embedded buses vias are typically used. A via is a conductive filled or conductive clad cavity defined in the substrate. In a typical arrangement, the conductive body residing in a via extends between an embedded bus and an exterior surface of the substrate. A component mounted on the exterior surface can be electrically connected to the embedded bus via an electrical connection to the conductive body inside the via.
The conductive body inside a via adds to the length of the conductive path between the components of an electronic assembly resulting in increased inductance in the connection path. Thus, the use of vias may lead to increased impedance particularly in high frequency applications.
In this arrangement, connections to the embedded buses and traces are required. Such connections are typically made outside the substrate to a contact on the bus/trace that is placed on the exterior surface of the substrate. Exposure of the conductive body at the exterior of the substrate may make the circuit including the body more readily subject to electrical interference.